Synthesis of Azuleno[1,2,3-<i>cd</i>]phenalene and Its π-Extended Buckybowl Derivative

Azulene-fused molecular carbons have sparked intense research interest in recent years. Herein, we report a facile three-step synthesis of azuleno[1,2,3-<i>cd</i>]phenalene (AzPn), a fused system combining azulene and phenalene units, achieving an overall yield of 39.7%. Furthermore, π-extended buckybowl derivatives (<b>7</b> and <b>8</b>) were synthesized through efficient intramolecular C-H arylation. X-ray analysis confirmed the structures of all three molecular carbons, revealing that the buckybowl derivative adopts a bowl-shaped geometry with a depth of 0.63 Å. Femtosecond transient absorption spectroscopy confirms the formation of triplet species via intersystem crossing in all three molecules following photoexcitation. These molecular carbons exhibit intriguing electronic properties with narrow energy gaps, positioning them as potential building blocks for functional molecular carbons.